Method of making parts of boilers



Jan. 22, 1924. 1,481,408

R. W. BIRCHFIELD METHOD OF MAKING PARTS OF BOILERS Filed Sept. 16 1921 3 Sheets-Sheet 1 R. W. BIRCHFIELD METHOD OF MAKING PARTS OF BOILERS Fan. 22 1924.

Filed Sept. 16, 1921 3 Sheets-Sheet 2 Jan. 22, 1924.

R. W. BIRCHFIELD METHOD OF MAKING PARTS OF BOILERS Filed p l6 1921 3 Sheets-Sheet 5 Patented Jan. 22, 11924.

A .umran stares ROBERT W. BIRCHFIELD, 0F TACOMA, WASHINGTON.

METHOD OF MAKING- PARTS OF BOIL.

Application filed September To all whom it may concern:

Be it known that I, ROBERT W. BIRCH- FIELD, a citizen of the United States. and a resident of Tacoma, in the county of Pierce and State of Washington, have invented certain new and useful Improvements in Methods of Making Parts of Boilers, of which the following'is a specification.

My invention relates to improvements in methods of making sheet metal structures and has special reference to improvements in making sheet metal shells for fire boxes of return flue boilers of the type used for steam and hot water heating and power purposes. My invention consists in taking a suitable fiat sheet metal blank and performing a few simple operations upon this blank to produce a firebox shell comprising, in a single piece, the crown sheet of a main combustion chamber and the side walls of the main combustion chamber and an auxiliary combustion chamber which rises above. one end of the main combustion chamber.

Another feature of my invention relates to the-productionof integral bent out flangesat the bottom edges of the side sheets to formthe bottom walls of side water legs of the boiler in which the fire box shell is used.

Other features, benefits and advantages will appear hereinafter.

My invention will be more readily understood by reference to the accompanying drawings forming part ofthis specification and in which Figure 1 is a longitudinal vertical central section'of a return tube boiler equipped with a fire box shell made in accordance with my invention';';;

Figs. 2 and 3 are vertical transverse sections taken on the lines 2-2 and 33 respectively of Fig. 1;

Fig. 4 is a lan view of a suitable rectangular blank 'or the fire box shell;

Fig. 5 illustrates the result of the first forming step andis a perspective View of the formed blank;

Fi 6 is a perspective view of the complete y formedshell;

Fig. 7 is a plan view of a blank similar to that shown in Fig. 4, but without the preliminary cuts;

Fig. 8 is a perspective View of a partly formed blank illustrating the result of the first operation on the blank shown in Fig. 7 and illustrates a slightly modified method; and i 16, 1921. Serial No. 501,068.

Fig, 9 is a perspective view illustrating the result of a second forming operation in the modified method, the completed article being shown in Fig. 6.

As a preliminary to describing myimproved method I will first describe the return tube boiler shown in Figs. 1 to 3, inclusive, which forms the subject matter of my copending application for Letters Patat ent, entitled Boiler, filed July 30, 1920, Se-

rial No. 399,999, and of which this present application is a continuation in part, ithaving been required that certain method claims originally filed in my said co-pending application, be divided out.

he boiler illustrated is of the horizontal return tube type it has an upper horizontal cylindrical body portion 1 from which depend side water legs 2, and forward and rear end water legs 3 and 4 respectively enclosing a fire space or furnace '5. The cylindrical body portion contains return fiues 6 in its upper half which extend from the forward end of the boiler to a rear auxiliary flue sheet 8 arranged atthe forward side of an auxiliary fire space 9 and through which the fire gases escape from the furnace space 5. The gases fiow from the furnace space 5 through the auxiliary space 9 then through the shorter fiues 7 to the forward end of the boiler where I provide a smoke box 10 connecting the upper and lower flues and cans-- ing the gases to return through the upper fines to the rear end of the boiler where they escape into a rear smoke box or flue 11 to be carried to the chimney.

The boiler, without the smoke boxes, is so built and constructed that its walls are, to all practical intents and purposes, a continuous sheet of uniform thickness and homogeneous throughout and without any rivets or riveted or calked joints.

In order to produce such a construction I provide a main outer sheet formed of WV U-shape, the middle portion forming the upper, cylindrical side 13 of the body 1 and the sides ofthe U extending down andforming'the outer walls of the side water legs 2. The inner wall of the boiler is formed of a second sheet 14 which is also formed into a general U-shape preferably with this distinction, however, that the bend of the U is reversed to form the lower part 15 of the cylindrical body portion 1 of the no boiler. The sides of the inner U-shaped sheet 14 form the inner walls 14' of the side water legs 2. For completing the side water legs at their lower ends-I provide one of the main sheets, preferably the inner sheet M, with horizontal outwardly extending flanges 16 at their lower edges which project outwardly to contact with the lower edges of the outer sheet, and I join the contacting iliary rear flue edges by welding, as shown at 17. At the rear part of the main inner sheet 14 the side walls extend up to about the middle line of the cylindrical part 1 of the boiler to form the sides of the auxiliary fire space 9.

The rear water leg 4 is built up of a rear flue sheet 18 which is cut to conform to and contact with the rear edge of the main outer boiler sheet 12 and isprovided in its upper part with suitable holes'19 for receiving the rear ends of the return fiues 6. The edges of this outer sheet are metallically joined to the rear edge of the outer sheet 12 by welding, as shown at 20,

The inner wall of the rear water leg 4: is

preferably formed of a sheet 21 which extends upwardly from the lower edge of the rear water leg to the top of the auxiliary furnace space 9 substantially parallel with the outer rear sheet 18. The upper part of this inner sheet extends forwardly to form the roof 22 of the auxiliary fire space 9 and is then bent downwardly to form the said auxiliary rear flue sheet 8. The edges of this inner sheet are metallically joined by welding, as shown at 23, to the adjacent edges of the inner main sheet 14:- The 'auxsheet 8 is provided with suitable openings for receiving the rear ends of the lower shorter tubes 7 The lower edges of the rear sheets 18 and 21 are joined together to close the lower end of the rear water leg, the outer sheet being provided with a horizontal inwardly extending flange 24 which is metallically joined at its inner edge to the lower edge of the inner sheet by welding, as shown at 25.

The forward water leg 3 is constructed similarly to the rear water leg 4. I provide an outer front sheet 26. which is cut to fit -within the forward edge of the outer U- shaped sheet 12 and is metallically joined thereto by' welding as shown at 27. I also provide an inner front sheet 28 which is cut to conform with the transverse shape of the inner main sheet 14, and is metallically united therewith at its edge by welding, as shown at 29.

The front water leg is provided with a suitable fire door 30 opening into the fire box, and this water leg is closed at its lower end in a similar manner to the closing of the other water legs.

I provide suitably spaced stay bolts 31 for bracing the inner and outer walls of the fire box and which'are preferably welded at their inner ends to the outer face of the agsneo tions of the fire box crown sheet and the outer sheet by stays 32 which are wholly within the boiler being suitably welded at their ends to the two portions they connect. This construction avoids the necessity of making any holes or openings in the walls of the boiler.

This present invention relates particularly to an improved method of forming the main inner wall or shell of the fire box and which wall comprises in asingle plate, the crown sheet 15 of the main combustioln chamber, the side walls 1 of the side water legs, which side walls constitute the side sheets 33 of the main combustion chamber and the side sheets 34: of the auxiliary combustion chamber. The auxiliary combustion chamber rises above one end of the main combustion chamber and its side walls 31 consequently rise above the side walls 32-3 of the main combustion chamber and above the crown sheet of the main combustion chamber.

In producing the inner shell 14, as best shown in Fig. 8, I preferably proceed as follows I provide a suitable blank 35 which is preferably rectangular in shape having a length 36 equal to the length of the fire box and having a width 36 which is sufficient to extend from the outer edge of the water leg flange 16 at one side, up, over and down go the similar edge at the opposite water I first preferably cut the blank inwardly at one end at the transverse center line for a portion of its length equal to the length of the auxiliary combustion space as shown at 37. Then I cut the blank transversely at the inner end of the first cut and ending at points between the sides of the blank as shown at 38 and which points are far enough from the side edges of the blank to leave sutlicient uncut portions to form the innerwalls of the side water legs. Then I bend the uncut residue of the blank along its longitudinal center line in alignment with the first cut 37 to bring the sides into parallelism to form the side sheets of the fire box, as shown in Fig. the portions 3L forming the side walls of the auxiliary combustion chamber separating from the main upon the article. This operation consists in bending the sides along longitudinal lines 40 at the juncture of the crown sheets with the side sheets toreverse the. direction of projection of the sides. As the plates are thus bent the parts 34 which form the sides of the auxiliary fire box remain in the planes of the sides of the blank and retain their relation with the main portions of the sides as best shown in Fig. 6. I may as a final operation bend the lower edges of the side sheets outwardly to form the bottoms 16 of the side water legs.

Instead of roceeding as above I may and often do ben the sheet before making the cuts 37 and 38, taking the blankets shown in Fig. 7 and performing thereon the first bending operation to produce the curved crown sheet portion 41 between the fiat parallel sides 42. Then I cut the partly formed blank on longitudinal and transverse lines 48 and 44 respectively similar to the cuts 37 and 38. Then I perform the second bending operation to reverse the direction of projection of the sides and to produce a downwardly curved crown sheet shown in Fig. 6. In this modified. method it is necessary after the second bending operation to flatten. out the parts 34L which form the sides of the auxiliary combustion chamber'which were originally curved in the first bending operation and which were separated from the main body of the sheet in the second bending operation as shown in Fig. 9 in which figure these parts are illustrated in their curved form. After 'flattening these parts out the shell is in exactly the same condition or shape shown in Fig. 6 as when pro-,

duced by the first described method.

It should be understood that I have greatly simplified and cheapened the manufacture of boilers of the return tube type and while I have described certain sequences of operation that my invention is not necessarily confined to the specific sequences described but that whether or not the specific steps are performed in the specific order described any method making use of the steps described would fall within the scope of the following claims.

I claim:

1. The method of manufacturing a com- I bined crown and side sheet for a boiler which consists in providing a suitable blank, cutting the blank inwardly at one end at the transverse center line for a portion only of the length of the blank, transverselycutting the blank at the inner end of" the firstment-ioned cut and ending at points between the sides of the blank, and bending the uncut residue of the blank to bring the sides into parallelism to form the side sheets and the intermediate portion to form the crown sheet. p

2. The method of manufacturing a combined crown and side sheet for a boiler which consists in providing a suitable blank, cutting the blank inwardly at one end at the transverse center line for a portion only of the length of the blank, transversely cutting the blank at the inner end of the firstmentioned cut and ending at points between the sides of the blank, and bending the uncut residue of theb lank to bring the side portions into parallelism to form the side sheets and the intermediate portions to form the crown sheet of a cylindrical boiler.

3. The method of manufacturing a combined crown and side sheet for a boiler which consists in providing a suitable blank, cutting the blank inwardly at one end at the transverse center line for a portion only of the length of the blank, transversely cutting the blank at the inner end of the.

during the bending operation by which the .side and crown sheets are formed.

4. In the manufacture of a boiler having an outer U-shaped sheet, the formation of a fire box shell which consists of the following, steps: providing a suitable blank, cutting it longitudinally inward at one end on its transverse center line for a portion only of its length, transversely cutting the blank at the inner end of the first cut and ending at points between the sides of the blank, bending the uncut portion of the blank to bring the sides into parallelism with each other and with the straight portions of the outer sheet and the intermediate portion into semi-cylindrical form on a radius substantially the same as that of the semicylindrical portion of the outer sheet.

5. The method of manufacturing a combined crown and side sheet for a boiler which consists in providing a suitable blank, cutting the blank inwardly at one end at the transverse center line for a portion only of the length of the blank, then transversely cutting the blank at the inner end of the first mentioned cut and ending at points between the sides of the blank, bending the uncut residue of the blank to form the end at the transverse center line for a portion only of the length of the blank, transversely cutting the blank at the inner end of the first-mentioned vcut and ending at points between the sides of the blank, bending the uncut residue of the middle portion into aconvex crown sheet and to bring the sides into parallelism, then bending the two sides of the sheet along lines which are approximately the sides of the convex crown sheet to reverse the relative direction .of projection of said sides and bring them into parallelism to produce a relatively concave crown sheet.

7. The method of making a combined crown and side sheet for a boiler fire box which has a main combustion space and an auxiliary combustion space rising above one end of the main combustion space, which method consists in providing a suitable fiat sheet blank, bending the blank between its side edges to bring its sides into parallelism to form side sheets and the. intermediate portion to form a crown sheet, and severing the sheet for a portion of its ''length along its transverse center line and transversely the blank to form at the inner end of the first cut and projccting the severed portions in the planes of the two side sheets to form side sheets for the auxiliary combustion space.

8 The method of making a combined crown and side sheet for a boiler fire box which has a main combustion space and an auxilary combustion space rising above one end of the main combustion space, which method consists in providing a suitable flat sheet blank, bending the blank between its side edges tobring its sides into parallelism to form side sheets and the intermediate portion to form a crown sheet, and severing the sheet for a portion of its its transverse center line and transversely at the inner end of the first cut, projecting the severed portions in the planes of the two side sheets to form side sheets for the auxiliary combustion space, and bending the extreme transverse edge portions of the sheet to form bottom closures for water legs.

Signed at \Vashington, District of Columbia, this 15th day of September, 1921.

ROBERT W. BIROHFIELD.

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